Messages in this thread | | | Date | Thu, 2 Feb 2023 15:44:35 -0800 | Subject | Re: [PATCH v2 02/18] x86/resctrl: Access per-rmid structures by index | From | Reinette Chatre <> |
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Hi James,
On 1/13/2023 9:54 AM, James Morse wrote: > Because of the differences between Intel RDT/AMD QoS and Arm's MPAM > monitors, RMID values on arm64 are not unique unless the CLOSID is > also included. Bitmaps like rmid_busy_llc need to be sized by the > number of unique entries for this resource. > > Add helpers to encode/decode the CLOSID and RMID to an index. The > domain's busy_rmid_llc and the rmid_ptrs[] array are then sized by
busy_rmid_llc -> rmid_busy_llc ?
Could you please also mention the MBM state impacted?
> index. On x86, this is always just the RMID. This gives resctrl a > unique value it can use to store monitor values, and allows MPAM to > decode the closid when reading the hardware counters. > > Tested-by: Shaopeng Tan <tan.shaopeng@fujitsu.com> > Signed-off-by: James Morse <james.morse@arm.com> > --- > Changes since v1: > * Added X86_BAD_CLOSID macro to make it clear what this value means > * Added second WARN_ON() for closid checking, and made both _ONCE() > --- > arch/x86/include/asm/resctrl.h | 24 ++++++++ > arch/x86/kernel/cpu/resctrl/internal.h | 2 + > arch/x86/kernel/cpu/resctrl/monitor.c | 79 +++++++++++++++++--------- > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 7 ++- > 4 files changed, 82 insertions(+), 30 deletions(-) > > diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h > index 52788f79786f..44d568f3577c 100644 > --- a/arch/x86/include/asm/resctrl.h > +++ b/arch/x86/include/asm/resctrl.h > @@ -7,6 +7,13 @@ > #include <linux/sched.h> > #include <linux/jump_label.h> > > +/* > + * This value can never be a valid CLOSID, and is used when mapping a > + * (closid, rmid) pair to an index and back. On x86 only the RMID is > + * needed. > + */ > +#define X86_RESCTRL_BAD_CLOSID ~0
Should this be moved to previous patch where first usage of ~0 appears?
Also, not having a size creates opportunity for inconsistencies. How about ((u32)~0) ?
> + > /** > * struct resctrl_pqr_state - State cache for the PQR MSR > * @cur_rmid: The cached Resource Monitoring ID > @@ -94,6 +101,23 @@ static inline void resctrl_sched_in(void) > __resctrl_sched_in(); > } > > +static inline u32 resctrl_arch_system_num_rmid_idx(void) > +{ > + /* RMID are independent numbers for x86. num_rmid_idx==num_rmid */ > + return boot_cpu_data.x86_cache_max_rmid + 1; > +}
It seems that this helper and its subsequent usage eliminates the need for struct rdt_resource::num_rmid? Are any users left?
Reinette
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